I started to merge two Lightroom catalogs 24 hours ago. It checked for duplicates for 5 hours and has been importing ever since. I'm using an upgraded Macbook Pro and only importing around 2000 images (approx 5MB in size each).
I really don't want to cancel and start over again. My Activity Monitor shows Lighroom taking most of the computers resources but the progress bar has been stuck at 25% completion since I started importing.